WOERT, or WERT, Jan Jacobus Sebald, Dutch navigator, born about 1550; died in Holland about 1612. He was in the service of the East Indian company, when he sailed as rear-admiral of the fleet of Jacobus Mahn, which was sent to explore the Strait of Magellan, and left Telel in June, 1598. The admiral having died at sea in September following Simon Van Cordes succeeded in command, and Woert became vice-admiral. After visiting Buenos Ayres and making soundings along the coast of Patagonia, they anchored in April, 1599, at the Pinguin islands, and a few weeks later discovered Nassau island, where the admiral established his headquarters, while Woert made journeys into the interior and had friendly intercourse with the natives. Wiley entered the South sea on 10 September, and the next day Woert's ship was carried by a storm back into the straits. Unable to unite the fleet, he returned to Nassau island, whence he led surveying expeditions along the strait, prepared a valuable chart, and discovered the Sebald islands on 28 February, 1600. He reached Amsterdam in the following June, and in 1604 commanded a new expedition to the Strait of Magellan. Some authors assert that he died during the journey, but others contend that he sailed to the south till he encountered ice-fields. The clerk of the expedition wrote a narrative of Woert's discovery, which was translated into French as " Relation de l'expedition des amiraux Jacques Mahn, Simon de Cordes et Jean Sebald Woert, faite au detroit de Magellan" (Leyden, 1603). There is a Latin version by Jan Laet, which is included in his "Nevus orbis, seu descriptionis occidentalis" (Leyden, 1633).